Congestive heart failure is a complex clinical syndrome characterized by exertional dyspnea, fatigue and, often, peripheral edema resulting from left ventricular dysfunction. The manifestation of congestive heart failure occurs secondary to a great variety of cardiac or systemic disorders that share a temporal or permanent loss of cardiac function. Recent progress in epidemiologic research has enabled the clear delineation of the predominant etiologic factors of congestive heart failure in Western societies. In particular, the long-term follow-up in the Framingham Heart Study has demonstrated that the majority of cases was predicted by one or more of four conditions: arterial hypertension, coronary artery disease, diabetes mellitus, and left ventricular hypertrophy (Levy D. et al. (1996) JAMA 275:1557-1562). In fact, the population attributable risk of these four factors combined accounted for about 90% of all cases with congestive heart failure.
Left ventricular hypertrophy as a complication of long-standing hypertension is a common factor in heart failure, even though the patient's blood pressure may be normal at the time congestive heart failure is diagnosed. In the absence of coronary artery disease and myocardial infarction, the left ventricular dysfunction in patients with hypertension often is predominantly a diastolic dysfunction with well-preserved chamber size and a normal ejection fraction.
Coronary artery disease is the most common etiology for left ventricular systolic dysfunction. Coronary artery disease (CAD) is a condition in which the heart muscle receives an inadequate amount of blood because of an interruption of its blood supply. It is presently the leading cause of death in the United States. Depending on the degree of interruption, symptoms can range from a mild chest pain to a full-scale heart attack. Generally, symptoms manifest when there is about a 75 percent narrowing of coronary artery lumina.
Stenotic and regurgitant valvular deformities, such as valvular stenosis, have also been well documented as contributing factors in ventricular dysfunction. Valvular stenosis is a narrowing, or stenosis, of one of the valves regulating blood flow in the heart. Stenosis may occur in the valve itself, most commonly in the mitral valve from rheumatic fever. All stenoses increase stress on the heart by making it work harder to push the blood through the abnormally narrow valve openings. As a result of mitral stenosis, blood pressure is increased. Angina pectoris and heart failure may accompany this disorder.
Finally, many diseases and toxins which directly affect the myocardium, can cause ventricular dysfunction. For example, excessive consumption of alcohol, diabetes mellitus and viral infections are associated with some causes of cardiomyopathy, whereas other cases may be genetic or idiopathic in nature.